This study will: 1) described and analyze the role of alcohol in the event which brought the individual to the emergency room and predict those who may be at risk for alcohol-related injuries from both emergency room and general population samples; 2) complement data already collected from emergency room patients in a California county to gain a clearer understanding of alcohol's part in emergencies for an entire county; 3) compare alcohol's involvement in emergency room admissions of a large health maintenance organization to those of the county and private hospitals in a single county; 4) compare health care utilization patterns an costs of those with alcohol-related injuries and illnesses in the emergency room to those without; and, 5) determine the potential of the emergency room visit to initiate treatment for alcohol problems, perhaps reducing inappropriate medical care utilization and costs. A probability sample of every fourth patient over the age of 18 admitted during a 6-week period to the emergency room in each of the three Kaiser Permanente medical centers in Contra Costa County will be selected to the interviewed and to be breathalyzed as an estimate of blood alcohol level at the time of the emergency room visit. This will yield a sample of 1596 patients. Patients will be interviewed regarding the problem which brought them to the emergency room, whether alcohol was a factor in that event, usual drinking patterns and times of higher consumption an problem- related drinking. A 50% probability sub-sample of the original sample will be selected for medical record abstraction to determine the use of outpatient medical services, associated costs and days of hospitalization for the year prior to the identifying emergency room visit and for 6 months following the visit. Similar medical record data will be available on a 5% probability sample of all Kaiser Permanente members in Contra Costa County for comparison. Kaiser Permanente emergency room data will be compared to that already collected from the county hospital and the three private hospitals in the county and will be combined with these data for a county description of alcohol and casualties. These county casualty data will be compared to comparable data on drinking patterns and alcohol-related problems which will have been collected in the general population of the county and in health and social service agencies in the county. County casualty data will also be combined with casualty data already collected form San Francisco General Hospital and with additional casualty cases being collected form the County hospital for a detailed analysis of alcohol by type and cause of injury within age and sex specific categories.